Glad to see that bypassing the tank was relatively easy. I used a clean milk jug full of gas and dropped the fuel line in there. With the tank taken out of the discussion, the mower failed to run at full throttle just as it did when connected to the tank. So, I'm back to looking at the carburetor. I had it apart [again] and cleaned it again which didn't solve the problem. Tomorrow, I plan to buy a new carburetor and give that a try. Aside from the tank, the filter, the lines, the pump, the solenoid, there's not much left (IMO). I'm justifying the expense by telling myself a 13 year old is due.
I appreciate everybody who posted an opinion on this forum. Thanks.